28 September 2008

Unexpected Darner

On Saturday, 9/27, I made a late afternoon trip over to Lenawee County to search for a couple of late season darners (Aeshna sp.) that would be new for the county. Onsted State Game Area near Cambridge Junction seemed like a good location since it includes several lakes and the River Raisin.

I initially stopped at the boat launch on the east shore of Grassy Lake and immediately saw a darner flying over the water. A 2nd one flew over my head and with a quick swing of the net, I found myself with an unusual male darner. The claspers were not wedge-shaped, but were fairly straight and there was a bump on the dorsal surface of abdominal segment 10. I initially thought of Canada Darner (Aeshna canadensis), that is, until I looked at the thorax. The mottled pattern clearly was that of a Mottled Darner (Aeshna clepsydra). A new species for me and the first for the county.

Searches of the adjacent lakes including One Mile Lake and Cleveland Lake didn't turn up any other darners so I returned to the original location for another hour.

There were ~4 males patrolling the shoreline and methodically searching the vegetation, just inches above the water of Grassy Lake.

At one point, one individual was checking me out, flying around me, checking out my face, then actually landing on my hat. I found this species to be very unwary and actually had a couple more instances of individuals fly near/around me while checking for prey.

Periodically individuals would land on tree trunks and, luckily, allowed a close approach.

Another darner landed in a dead tree, almost beyond the reach of my net. However, there were branches in the way so I fished my net up to the trunk. Surprisingly, the darner didn't fly and I was able to slowly position my net next to this dragonfly and get it to move onto the hoop. I was able to move the net out from the branches, and capture it with a quick flick of the wrist.

Surprise, another Mottled Darner (A. clepsydra).

Here's a closeup of the thoracic pattern.

...and the claspers

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